Abstract. This K24 renewal will enable the investigator to continue a very successful transdisciplinary mentorship program for digital health research focused on obesity and cardiovascular disease (CVD) prevention. The candidate currently has 14 mentees ranging from high school to junior faculty level. In the four years her K24 has been funded her mentees earned 104 co-authorships on papers and submitted 40 grants (31 thus far) under her mentorship. The proposed mentorship plan will build additional training experiences into her mentorship program by providing mentees with a transdisciplinary mentoring experience that represents experts in behavioral science, preventive cardiology, health informatics, data science, and innovative research designs. Mentees from collaborating labs at UMass Medical School, Penn State University, and Worcester Polytechnic Institute will ?embed? in each other's lab to learn a broad range of digital health research skills with an emphasis on data science, innovative methodologies, and designing innovations with commercial potential. Mentees will learn how to: utilize mobile apps and online social networks in their research; analyze social network data; conduct qualitative and quantitative data analyses; leverage innovative research designs (e.g., MOST); employ behavior change strategies in mobile and social network environments; design preliminary studies; and write grants. The candidate's training goals are to expand her research into implementation, dissemination, and larger scale program projects; enhance her mentorship of young investigators seeking to study innovative technologies; increase capacity to translate NIH-funded digital health innovations into the healthcare economy; and increase capacity of the UConn Center for mHealth and Social Media to build a national reputation for training in behavioral digital health research in CVD risk reduction. The overarching goal of the research plan is to test ways to leverage social media to deliver health behavior programming in ways that maximize efficacy, scalability, and dissemination potential. Three research aims are proposed, all of which test the efficacy of cardiovascular disease prevention and/or weight management programs delivered via social media. The first aim proposes to test the efficacy of a Facebook-delivered CVD prevention healthy lifestyle program for young women. The second aim is to test the efficacy of a similar CVD prevention program but tailored to adult family members in families that have already been impacted by a life-threatening disease. This Facebook-delivered CVD prevention program will leverage family ties to promote behavior change. The third aim is to conduct a feasibility trial of multiphase optimization strategy (MOST) study which will test the optimal formats for goal setting and problem solving messages in a social media delivered weight loss intervention. This work will provide preliminary data for 3 R01 applications. The proposed work will produce training experiences and data that will contribute to the mentorship of the next generation of researchers who will have transdisciplinary expertise to leverage social media in the delivery of CVD prevention interventions.